The p38 kinase is a mitogen-activated protein (MAP) kinase that belongs to the serine/threonine kinase superfamily. This kinase is activated by extracellular stresses such as heat, UV light, and osmotic stress, as well as by inflammatory stimuli such as lipopolysaccharide. When activated, p38 kinase phosphorylates intracellular protein substrates that regulate the biosynthesis of the pro-inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β). These cytokines are implicated in the pathology of a number of chronic inflammatory disorders (Lee, et al., Ann. N.Y. Acad. Sci., 696, 149-170 (1993); Muller-Ladner, Curr. Opin. Rheumatol., 8, 210-220 (1996)), cardiovascular and central nervous system disorders (Salituro, et al., Current Medicinal Chemistry, 6, 807-823 (1999)), and autoimmune disorders (Pargellis, et al., Nature Structural Biology, 9(4), 268-272 (2002)).
A number of compounds within the pyridinylimidazole (WO9621452, WO9725045, U.S. Pat. No. 5,656,644, U.S. Pat. No. 5,686,455, U.S. Pat. No. 5,717,100, WO9712876, WO9821957, WO9847892, WO99903837, WO9901449, WO0061576, WO0172737) and pyrimidinyl-imidazole (WO9725048, WO9901452, WO9725046, WO9932121, WO9901131, WO9901130, WO9901136, WO9807452, WO9747618, WO9856788, WO9857996) structural platforms have been identified as inhibitors of p38 kinase or as cytokine inhibitors. Selective inhibitors of p38 kinase are known to suppress the expression of TNF-α and IL-1β (McKenna, et al., J. Med. Chem., 45(11), 2173-2184 (2002)). Anti-inflammatory activity for compounds within the pyrimidinylimidazole structural platform has been reported (Lantos, et al., J. Med. Chem., 27, 72-75 (1984)), and a number of inhibitors of p38 kinase are under active investigation for the treatment of a variety of disorders (Boehm and Adams, Exp. Opin. Ther. Patents, 10(1), 25-37 (2000)). There remains a need for treatment in this field for compounds that are cytokine suppressive, i.e., compounds that are capable of inhibiting p38 kinase.
The present invention provides new inhibitors of p38 kinase useful for the treatment of conditions resulting from excessive cytokine production.